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Tue, 31 Mar 2020 09:48:05 +0000 (UTC) Received: from maximlenovopc.usersys.redhat.com (unknown [10.35.206.223]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9306A96B87; Tue, 31 Mar 2020 09:48:03 +0000 (UTC) Message-ID: Subject: Re: [PATCH v6 09/42] nvme: add max_ioqpairs device parameter From: Maxim Levitsky To: Klaus Birkelund Jensen Date: Tue, 31 Mar 2020 12:48:02 +0300 In-Reply-To: <20200331054010.4wfanhp56nvemb46@apples.localdomain> References: <20200316142928.153431-1-its@irrelevant.dk> <20200316142928.153431-10-its@irrelevant.dk> <20200331054010.4wfanhp56nvemb46@apples.localdomain> Mime-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] [fuzzy] X-Received-From: 207.211.31.120 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Kevin Wolf , Beata Michalska , qemu-block@nongnu.org, qemu-devel@nongnu.org, Max Reitz , Keith Busch , Javier Gonzalez Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Tue, 2020-03-31 at 07:40 +0200, Klaus Birkelund Jensen wrote: > On Mar 25 12:39, Maxim Levitsky wrote: > > On Mon, 2020-03-16 at 07:28 -0700, Klaus Jensen wrote: > > > From: Klaus Jensen > > > > > > The num_queues device paramater has a slightly confusing meaning because > > > it accounts for the admin queue pair which is not really optional. > > > Secondly, it is really a maximum value of queues allowed. > > > > > > Add a new max_ioqpairs parameter that only accounts for I/O queue pairs, > > > but keep num_queues for compatibility. > > > > > > Signed-off-by: Klaus Jensen > > > --- > > > hw/block/nvme.c | 45 ++++++++++++++++++++++++++------------------- > > > hw/block/nvme.h | 4 +++- > > > 2 files changed, 29 insertions(+), 20 deletions(-) > > > > > > diff --git a/hw/block/nvme.c b/hw/block/nvme.c > > > index 7cf7cf55143e..7dfd8a1a392d 100644 > > > --- a/hw/block/nvme.c > > > +++ b/hw/block/nvme.c > > > @@ -1332,9 +1333,15 @@ static void nvme_realize(PCIDevice *pci_dev, Error **errp) > > > int64_t bs_size; > > > uint8_t *pci_conf; > > > > > > - if (!n->params.num_queues) { > > > - error_setg(errp, "num_queues can't be zero"); > > > - return; > > > + if (n->params.num_queues) { > > > + warn_report("nvme: num_queues is deprecated; please use max_ioqpairs " > > > + "instead"); > > > + > > > + n->params.max_ioqpairs = n->params.num_queues - 1; > > > + } > > > + > > > + if (!n->params.max_ioqpairs) { > > > + error_setg(errp, "max_ioqpairs can't be less than 1"); > > > } > > > > This is not even a nitpick, but just and idea. > > > > It might be worth it to allow max_ioqpairs=0 to simulate a 'broken' > > nvme controller. I know that kernel has special handling for such controllers, > > which include only creation of the control character device (/dev/nvme*) through > > which the user can submit commands to try and 'fix' the controller (by re-uploading firmware > > maybe or something like that). > > > > > > Not sure about the implications of this, so I'll leave that on the TODO > :) But a controller with no I/O queues is an "Administrative Controller" > and perfectly legal in NVMe v1.4 AFAIK. That what I was thinking as well. Keeping this on a TODO list is perfectly fine. > > > > > > > if (!n->conf.blk) { > > > @@ -1365,19 +1372,19 @@ static void nvme_realize(PCIDevice *pci_dev, Error **errp) > > > pcie_endpoint_cap_init(pci_dev, 0x80); > > > > > > n->num_namespaces = 1; > > > - n->reg_size = pow2ceil(0x1004 + 2 * (n->params.num_queues + 1) * 4); > > > + n->reg_size = pow2ceil(0x1008 + 2 * (n->params.max_ioqpairs) * 4); > > > > I hate to say it, but it looks like this thing (which I mentioned to you in V5) > > was pre-existing bug, which is indeed fixed now. > > In theory such fixes should go to separate patches, but in this case, I guess it would > > be too much to ask for it. > > Maybe mention this in the commit message instead, so that this fix doesn't stay hidden like that? > > > > > > I'm convinced now. I have added a preparatory bugfix patch before this > patch. Thanks a lot!. Sorry for not noticing it before. > > > > > Reviewed-by: Maxim Levitsky > > > > Best regards, > > Maxim Levitsky > > Best regards, Maxim Levitsky > >